Autism rates continue to rise, according to a new government survey, but the skyrocketing figures don’t necessarily mean the disorder is increasing.

According to the latest estimate, released on Thursday by the Centers for Disease Control and Prevention (CDC), 1 in 88 children in the U.S. has an autism spectrum disorder (ASD) — a nearly 25% increase from 2006, when the rate was 1 in 110, and a stunning 78% increase since 2000–02, when the CDC first began tracking the disorder and estimated the rate at 1 in 150 children.

Much of the surge, experts acknowledge, may be due to better diagnosis, wider awareness and broader definitions of autism. Autism used to be diagnosed only in children with severe language and social problems and repetitive behaviors, but several years ago, researchers expanded the criteria for diagnosis to also include autism spectrum disorders — a wider range of developmental conditions associated with autism. These conditions include Asperger’s syndrome, which describes children who are high functioning but exhibit milder symptoms of social impairment or learning problems, and pervasive developmental disorder not otherwise specified (PDD-NOS), a diagnosis that is easier to get.

Greater awareness of autism by parents, doctors and school administrators, along with a growing push to help all affected children learn and socialize, may also be fueling the uptick. “Doctors have gotten better at diagnosing the condition, and communities have gotten better at providing services for those affected by autism,” Dr. Thomas Frieden, director of the CDC, told reporters in a conference call. “At this point, I think it’s a possibility that the increase in identification of autism is entirely the result of better detection. We don’t know whether or not that is the case, but it is a possibility.”

Mark Roithmayr, president of Autism Speaks, an autism research and advocacy group, concedes that such factors may figure into the swelling of cases but argues that they likely account for only about half the increase. “Only part of the increase can be explained by better and broader diagnoses,” he said on the same call. “There is a great unknown. Something is going on here, and we don’t know.”

The latest CDC numbers come from the Autism and Developmental Disabilities Monitoring Network, a comprehensive program covering 14 states, in which trained reviewers examine medical and school records of 8-year-olds for descriptions or diagnoses of autism or ASDs.

Tracking the prevalence of autism has always been controversial, and experts still can’t agree on exactly how common the disorder is, since its definition continues to shift. The rate may drop again by year’s end, when a new definition of autism is slated to be included in the fifth revision of the standard manual for mental illness, the DSM-V; the updated definition is expected to focus more exclusively on core autism cases and exclude Asperger’s and PDD-NOS, which a growing number of experts believe to be distinct from true autism. The current CDC analysis did not break down ASD diagnoses by subtype.

These changes may have serious implications for many families that rely on special programs to help their children succeed in school or learn how to socialize; the new definition may mean some families will no longer be eligible for the services. But experts say a change in definition shouldn’t negatively affect many families, since such services don’t require a diagnosis of autism per se. In fact, a clearer understanding of what autism is may help children receive better and more targeted care. “The last definition of autism was made in 1994, and we know a whole lot more now than we did in 1994 about autism,” Dr. Susan Hyman, chair of the autism subcommittee at the American Academy of Pediatrics, told reporters. “There’s a possibility that the new definition will be better for children and better for their families.”

One thing a more refined definition could do is help parents recognize signs of autism earlier and doctors diagnose the disorder sooner. Increasingly, research shows that children benefit from intervention — whether that includes medication, behavioral therapy or additional help in school — sooner. “What we do know for certain is that autism is common, and children with autism need to be effectively served,” said Frieden. “We need to increase the number of kids detected, the number of kids detected early and the number of kids enrolled in services early.”

Parents should be talking to their pediatricians if they have concerns about their baby’s behavior or missed developmental milestones, such as if they fail to start talking or making eye contact with others at the typical age. Experts urge parents and doctors to identify children with autism as early as 18 months, so they can benefit most from behavioral treatments. In the current CDC study, most children weren’t diagnosed until age 4, which was six months earlier than the previous survey in 2006 but still too late to make significant changes to a child’s brain development. “It’s important that parents who have any concerns bring them up,” said Hyman. “Any concern has to be taken seriously. Don’t defer.”